Runway light

ABSTRACT

An inset runway light having a shallow optical system for collecting the light generated by a light source and elevating and bending the light rays so that the emitted light hugs the runway in a prescribed pattern and direction. The lightcollecting ends of a plurality of flexible light-conveying conduits are arranged in contact with each other in longitudinal and peripheral rows on a transparent support tube surrounding the light source and are bonded thereto to pick up the generated light. The light exit ends of the conduits are hermetically sealed in an exit port of the light fixture and may be pointed substantially parallel to the surface of the runway to emit the light over a light ramp parallel with the surface of the runway. The receiving end emitting ends of the light conduits may be enlarged or reduced in size and formed of any cross section to accommodate the geometry of the exit port and the transparent support tube which may also serve as the evaporator for a refrigerator conducting heat to the cover for the fixture.

I United States Patent m13,567,917

[72] inventor William C. Daley 3,114,283 12/1963 Gruner 240/1(X) Suflield, Conn. 3,331,956 7/1967 Hough 240/ 1.2 [21] P 7504537 Primary Examiner-Samuel S. Matthews gg s Assistant ExaminerRussell E. Adams, Jr.

0 [731 Assignee Structural Electric Products Corp. Attorney Pmtzman Hayes Kalb & Chilton Windsor Locks, Conn.

ABSTRACT; An inset runway light having a shallow optical system for collecting the light generated by a light source and elevating and bending the light rays so that the emitted light [54] RUNWAY LIGHT hugs the runway in a prescribed pattem and direction. "ljhe 6 Claims 3 Drawing Figs light-collecting ends of a plurallty of flexible light-conveying conduits are arranged In contact with each other in longitu- [52] US. Cl 240/L2, ding] and peripheral [0W5 on a transparent sup t t b 240/1El rounding the light source and are bonded thereto to pick up [51] Int. Cl B64f 1/20 the generated light The light exit ends of {he cond it ar h r. [50] Field of Search 240/1 (ei), metically sealed in an exit port of the light fixture and may be 1 350/96, 1 10, pointed substantially parallel to the surface of the runway to 56 emit the light over a light ramp parallel with the surface of the I 1 References c'ted runway. The receiving end emitting ends of the light conduits UNITED STATES PATENTS may be enlarged or reduced in size and formed of any cross 2,354,367 7/1944 Ford 240/1 (X) sectionto accommodate the geometry of the exit port and the 2,507,909 5/1950 Kaysen 24Q/10( X) transparent support tube which may also serve as the evapora- 2,639,528 S/ 1953 Ochsner 240/1(X) tor for a refrigerator conducting heat to the cover for the fix- 3,112,890 12/1963 Snelling 240/47(X) ture.

RUNWAY LIGHT This invention relates generally to roadway and airport runway and other vehicle guidance lights and particularly to the inset type high intensity light in which the light source is disposed below the runway surface and includes an optical system to elevate and cause the emitted light to hug the runway.

Modern flush and semiflush inset aircraft visual guidance lights in runways, taxiways and approach areas are required to emit high intensity useful light to provide necessary illumination for safety purposes. The light source for such lights are of the filament type wherein the filament is encased in a quartz envelope disposed below the surface of the runway in a fixture having a heavy cover to protect the lamp from the shock and weight of aircraft traveling over it and of snowplows used in clearing snow. The optical systems heretofore required to collect, elevate and deflect the light to direct the emitted light according to the required pattern have been inefficient requiring the use of an oversize light source in order to provide the required useful light emitted from the fixture resulting in the generation of excess heat by the light source which has been the limiting factor in the design of the runway lights.

The present invention overcomes the aforementioned difficulties by providing an inset light with a novel shallow optical system for collecting and directing a greater proportion of the light generated so that it is emitted as useful light.

Another object of this invention is to provide an inset light of the type described having a shallow optical system adapted to deliver increased useful light for aircraft guidance. Included in this object is the provision of an optical system which makes possible a reduction in the size of the light source for a given amount of useful emitted light and the advantages incident thereto and resulting therefrom. v

A further object of the invention is to provide an inset light having a shallow optical system which collects, conveys and directs a greater portion of the light generated into emitted light meeting the prescribed requirements for useful light for vehicle guidance applications.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which is exemplified in the construction hereafter set forth, and the scope of the invention is indicated in the appended claims.

In the Drawing:

FIG. 1 is a fragmentary cross-sectional view of an inset light fixture embodying the present invention;

FIG. 2 is a fragmentary perspective view, partly broken away, of the novel optical system for collecting and directing the light from the light source in the embodiment of FIG. 1; and

FIG. 3 is a fragmentary sectional view ofa modified form of the invention incorporating a fluid heat dissipation means.

Referring now to the drawings in greater detail, FIG. 1 shows an illustrative embodiment of the invention including a watertight closed cylindrical housing or receptacle embedded below the surface G of a runway 12 in a typical installation. As shown, the receptacle 10 provides an inwardly directed peripheral flange 14 to which the top cover 16 is sealed by O-ring l8 and is removably secured to receptacle 10 by any conventional means such as bolts (not shown) to index and point the emitted light beam along the desired path, as, for example, along the centerline of a runway. The optical system includes a light source or lamp 20 having a filament 24 and may be mounted within the fixture in any convenient manner, as, for example, by being secured to the cover plate 16 by mounting blocks (not shown) with the filament 24 being connected across an electrical power supply. As shown, the cover plate 16 is provided with an exit port 25 through which the light is emitted from the fixture.

In accordance with this invention, means forming a novel light collecting, conveying and directing shallow optical system is provided. In the illustrated preferred embodiment, a plurality of light-conveying conduits 26 each having one end pointed in a direction generally toward the filament 24. The other end of each light-conveying conduit 26 is pointed Through the exit port 25 of the cover plate 16 so as to direct the light collected from the filament 24 along a desired path hugging the runway. As shown in FIGS. 1 and 2, the light entrance ends 30 of each of the light-conveying conduits 26 are disposed in longitudinally and peripherally extending rows surrounding the lamp 20 and are generally pointed toward the filament 24 to receive light therefrom. As shown, the ends 30 of the several light conduits 26 are of square cross section and are secured in position in longitudinal and peripheral contact with each other by being potted or bonded to a transparent tubular member 32 surrounding the lamp 20. As illustrated, the member 32 is sized so as to accommodate the light receiving ends 30 of the light-conveying conduits 26 in touching relationship so as to intercept all of tee light generated by the filament 24 except that emerging from the ends of the tube 32. The other ends 34 of the light-conveying conduits 26 may be bundled together in close proximity with respect to each other and shaped to conform with the exit port 25 to emit light at the desired angle in accordance with the desired pattern relative to the runway. For example, it is a general requirement of runway lights to have a high intensity core light and this may be achieved by connecting the light-conveying conduits 26a having their receiving ends 30 disposedradially outwardly from the center of the filament 24 (and hence the conduits which pick up the most light), so that their emitting ends 34 are at the center of the shaped bundle in the exit port 25. The shaped emitting ends 34 of the light-conveying conduits 26 may be bonded or potted together in any suitable manner and sealed within exit port 25 so as to hermetically seal the fixture and may be used alone or in conjunction with a refracting lens over the emitting ends 34 thereof. Moreover, the angle at which the light is emitted from the fixture is not governed by the rigid limitations of any lenses and prisms utilized in collecting, elevating and deflecting the light generated by the filament 24, as in conventional optical systems and the light emitted through the exit port 25 may, for example, be pointed parallel to surface G of the runway by the simple expedient of pointing emitting ends 34 of the light-conveying conduits 26 and supporting them within the walls of exit port 25 in a position parallel to the runway. In this connection, the surface 16a of the light ramp of cover 16 may be parallel with and at the level of the runway surface G rather than angled upwardly as in conventional designs to reduce the possible photometric losses resulting from degradation of emitted light by water or other matter collected on the ramp 16a.

By locating the ends of the light receiving ends 30 of 48 conveying conduits 26 having a uniform cross section of W'X'A" in longitudinal and peripheral rows as illustrated, the light-collecting ends 30 will cover the area of the lamp which emits to percent of the lumens. In view of the high percentage of capture of the lumens generated by the light source 20 by the optical system of such a design, a system efficiency of about three to five times that of conventional optical systems presently being used may be achieved. Moreover, while lightreceiving ends 30 of the light conduits 26 are shown as being pointed in a radial direction relative to tube 32, the tube 32 may be provided with a convexly longitudinal curvature so as to point each of the light collecting ends 30 of the light-conveying conduits more directly toward the filament of light source 24. Such a design would further contribute to the efficiency of the optical system of this invention since the efficiency of the preferred light-conveying conduits 26 decreases where the entering light rays approach at an angle of say 35 or more.

A light-conveying conduit 26 suitable for use in the practice of this invention may be formed by a bundle of a multiplicity of optically distinct fibers of small diameter and comprising highly transparent glass or plastic cores coated with a glass or plastic covering of lower refractive index. The ends of the bundles of fibers are secured or bonded together to preserve the integrity of the ends of the conduit and desirably to that the individual fibers at the two ends have a similar placement or orientation relative to each other and may be sheathed in whole or in part by a protective covering such as a resilient epoxy or vinyl resin.

A light-conveying conduit formed of a bundle of fibers as described is inherently flexible along any longitudinal portion thereof in which the individual fibers are not bonded together so that the intermediate portions of the lightconveying conduits 26 may be made flexible to facilitate the installation of the optical system regardless of manufacturing variations and tolerance without stressing the conduits. Moreover, with only the ends of the light-conveying conduits 26 being bonded together and rigid, the emitting ends 34 of the conduits 26 may be shaped to conform to a curved contour in the exit port 25 of the cover 16 during installation.

While this invention reduces the high light intensity requirements of (and the heat generated by) the light source 20 due to increased efficiency, the design further accommodates the use of an efficient radiator means for dissipating the heat generated by the filament 24 to the cover plate 16 as shown in FIG. 3. As shown in FIG. 3, the transparent tube 32 may also serve as a heat absorbing chamber for a refrigerant or liquid 36 which absorbs the heat from the quartz envelope of the lamp 20 and rises into the heat dissipating chamber 38 through passages 40. In the heat dissipating chamber 38 the heat carried by the fluid is passed to the atmosphere through the cover plate 16 so that the cooled fluid drops back into the heat absorbing chamber formed by the tubular member 32 for recycling. As illustrated, the ends of the last tube 32 are sealed by plugs 42 having apertures which also sealingly engage the passages 40 and the protruding ends 44 of the lamp 20.

While the invention has been illustrated by the design of a lamp fixture having a single exit port 25, it is apparent that it can be applied to a fixture having more than one exit port. Also, the light-conveying conduits 26 formed as described above may be shaped so that their ends are enlarged, reduced in size, or made to any desired geometric configuration so that the light-receiving ends 36 may, for example, be enlarged to cover the entire surface of an enlarged tube 32 to receive the light from the lamp 20 regardless of the geometrical configuration of tube 32 or reduced in cross section to accommodate an exit port of reduced dimension and to shape the output beam.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure abovedescribed will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

lclaim:

l. A shallow optical system for a substantially inset runway light fixture comprising a light source providing a divergent light beam, a transparent tubular member surrounding said light source, a plurality of light-conveying conduits having their light-receiving ends, secured to said transparent tubular member in substantially contacting relationship with each other and extending longitudinally and peripherally thereof to surround the light source and capture the light rays generated thereby, said conduits having their light-emitting ends pointed to direct and emit the collected light from the fixture in a prescribed pattern and direction.

2. A device as recited in claim 1 wherein the light fixture is hermetically sealed and is provided with an exit port, wherein the light-emitting ends of said light-conveying conduits are sealed within the exit port.

3. A device as recited in claim 1 wherein the intermediate portions of the light-conveying conduits are flexible and the emitting ends thereof are bonded together in sealed relationshi A device as recited in claim 3 wherein the light-receiving 

1. A shallow optical system for a substantially inset runway light fixture comprising a light source providing a divergent light beam, a transparent tubular member surrounding said light source, a plurality of light-conveying conduits having their light-receiving ends secured to said transparent tubular member in substantially contacting relationship with each other and extending longitudinally and peripherally thereof to surround the light source and capture the light rays generated thereby, said conduits having their light-emitting ends pointed to direct and emit the collected light from the fixture in a prescribed pattern and direction.
 2. A device as recited in claim 1 wherein the light fixture is hermetically sealed and is provided with an exit port, wherein the light-emitting ends of said light-conveying conduits are sealed within the exit port.
 3. A device as recited in claim 1 wherein the intermediate portions of the light-conveying conduits are flexible and the emitting ends thereof are bonded together in sealed relationship.
 4. A device as recited in claim 3 wherein the light-receiving ends of the light-receiving conduits are arranged in longitudinally and peripherally extending rows along the transparent tubular member.
 5. A device as recited in claim 4 wherein radiator means are provided for cooling the light source.
 6. A device as recited in claim 5 wherein the ends of the tubular member are sealed and a refrigerant in the tubular member is vaporized by the heat of the light source and is connected with a condenser chamber contacting the cover of the fixture. 